Transmission-side communication apparatus and retranmsission control method

Abstract

A retransmission control method of a transmission-side communication apparatus, which transmits a packet to a reception-side communication apparatus in a radio communication system that supports adaptive modulation and coding (AMC) and hybrid automatic retransmission control (HARQ), comprises: a step (S 110 to S 125 ) of transmitting an initially transmitted packet to the reception-side communication apparatus by using a first MCS; and a step (Step S 155 ) of transmitting a new initially transmitted packet to the reception-side communication apparatus by using a second MCS, instead of transmission of a retransmitted packet that is combined with the initially transmitted packet in the reception-side communication apparatus, when the second MCS different from the first MCS is used at the time of retransmission (step s 150; NO), the new initially transmitted packet including retransmission data to be transmitted through the retransmitted packet.

1 . A transmission-side communication apparatus, which transmits a packet to a reception-side communication apparatus in a radio communication system that supports adaptive modulation and coding and hybrid automatic retransmission control, comprising:
 a transmission unit that transmits an initially transmitted packet and a retransmitted packet to the reception-side communication apparatus, the retransmitted packet being combined with the initially transmitted packet in the reception-side communication apparatus; and   a control unit that controls, when a modulation and coding scheme different from the modulation and coding scheme used at the time of transmission of the initially transmitted packet is used at the time of retransmission, the transmission unit to transmit, instead of transmitting the retransmitted packet, a new initially transmitted packet including retransmission data to be transmitted, by using the different modulation and coding scheme, through the retransmitted packet, to the reception-side communication apparatus.   
     
     
         2 . The transmission-side communication apparatus according to  claim 1 , wherein
 when the different modulation and coding scheme is used at the time of retransmission due to deterioration of a radio state between the transmission-side communication apparatus and the reception-side communication apparatus, the control unit controls the transmission unit to transmit, instead of transmitting the retransmitted packet, the new initially transmitted packet to the reception-side communication apparatus by using the different modulation and coding scheme.   
     
     
         3 . The transmission-side communication apparatus according to  claim 1 , wherein
 the transmission unit comprises:
 a first retransmission queue unit that holds the retransmission data to be transmitted through the retransmitted packet; 
 a second retransmission queue unit; and 
 a transmission queue unit that holds data to be newly transmitted, 
 the control unit controls the transmission unit to include the retransmission data held in the first retransmission queue unit into the retransmitted packet and to transmit the retransmitted packet when a modulation and coding scheme, which is equal to the modulation and coding scheme used at the time of transmission of the initially transmitted packet, is used at the time of retransmission, and 
   the control unit moves the retransmission data held in the first retransmission queue unit to the second retransmission queue unit and then controls the transmission unit to include the retransmission data into the new initially transmitted packet in sequence of priority of retransmission data held in the second retransmission queue unit and data held in the transmission queue unit, to transmit the new initially transmitted packet when the different modulation and coding scheme is used at the time of retransmission.   
     
     
         4 . A retransmission control method of a transmission-side communication apparatus, which transmits a packet to a reception-side communication apparatus in a radio communication system that supports adaptive modulation and coding and hybrid automatic retransmission control, comprising:
 a step of transmitting an initially transmitted packet to the reception-side communication apparatus by using a first modulation and coding scheme; and   a step of transmitting a new initially transmitted packet to the reception-side communication apparatus by using a second modulation and coding scheme, instead of transmission of a retransmitted packet that is combined with the initially transmitted packet in the reception-side communication apparatus, when the second modulation and coding scheme different from the first modulation and coding scheme is used at the time of retransmission, the new initially transmitted packet including retransmission data to be transmitted through the retransmitted packet.   
     
     
         5 . The retransmission control method according to  claim 4 , wherein,
 in the step of transmitting the new initially transmitted packet, when the second modulation and coding scheme is used at the time of retransmission due to deterioration of a radio state between the transmission-side communication apparatus and the reception-side communication apparatus, the new initially transmitted packet is transmitted, instead of the retransmitted packet being transmitted, to the reception-side communication apparatus by using the second modulation and coding scheme.   
     
     
         6 . The retransmission control method according to  claim 4 , wherein
 the transmission-side communication apparatus comprises:
 a first retransmission queue unit that holds the retransmission data to be transmitted through the retransmitted packet; 
 a second retransmission queue unit; and 
 a transmission queue unit that holds data to be newly transmitted, and 
   the step of transmitting the new initially transmitted packet comprises:
 a step of moving the retransmission data held in the first retransmission queue unit to the second retransmission queue unit, and 
 a step of including the retransmission data into the new initially transmitted packet in sequence of priority of retransmission data held in the second retransmission queue unit and data held in the transmission queue unit.